Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 07/14/89

Final Date: 08/30/90

Deleted Date:

Edwards Air Force Base, which is used for aircraft research and development, covers approximately 301,000 acres. The Main/South Base at the western edge of Rogers Dry Lake is primarily used for maintaining and refueling aircraft. Large amounts of fuel and solvents have been spilled and poor disposal practices have resulted in the release of volatile organic compounds (VOCs), metals, and other chemicals to the ground. Other contaminated areas include a remote elevated ridge where rocket engine testing activities resulted in 4 major and extensive groundwater contamination plumes (PCE, TCE, perchlorate) and DNAPLs in fractured bedrock, an abandoned sanitary landfill containing heavy metals and an area where electroplating wastes were dumped. The North Base, located 5 miles northeast of the Main Base area, has a drum storage site at the northern end of Rogers Dry Lake and three unlined surface impoundments where wastes were poured during the 1960s and 1970s. A total of eight areas are being studied to confirm the presence of contaminants. The 13,800 employees at Edwards Air Force Base obtain some of their drinking water from wells located within 3 miles of the Main/South Base. Lancaster and small communities are located miles away from base operations.

Contaminants and Risks

Contaminated Media

Groundwater

Surface Water

Air

Soil and Sludges

Environmentally Sensitive Area

Groundwater and soils have been contaminated with various solvent and fuel VOCs, BTEX, perchlorate, 1,4-dioxane , NDMA, and various metals. In addition to these contaminants, landfills may contain UXO or other munitions related materials. People may face a health risk by drinking contaminated groundwater, making contact with some soils or materials in landfills, or breathing indoor air in some buildings located above or near VOC-contaminated media. Some surface water is threatened by seeps of TCE contaminated groundwater: and, in significant rainy seasons, occasional standing water on normally dry lake beds can pose a threat to carry surface salts down potential conduits of groundwater remediation and monitoring well infrastructure located on the lake bed or cracking of surface clays due to subsidence from localized pumping. Edwards is also home to the threatened desert tortoise and its designated critical habitat that encompasses 65,569 acres.

Who is Involved

Investigation and Cleanup Activities

The Air Force used many immediate actions (Interim Removal Actions) to begin cleanup of contaminated soil, debris, and groundwater. Also, some field-scale treatability studies have removed significant contaminant mass. The Air Force tested and continues to test a variety of innovative treatment technologies at Edwards, while they complete the remedial investigations of different areas of the base. An extensive groundwater monitoring program is already underway. Many of the 471 potential contamination sites identified in 10 operable unit areas have already been investigated enough to determine that they need no further investigation or no further action because of insignificant residual contamination. The Air Force will perform final cleanup actions for a variety of sites in the operable unit areas, after they select final remedies in Records of Decision. Currently, eight RODs have been signed and nine more are anticipated by EPA through 2020. The Air Force is currently exploring ways to accelerate many of these ROD schedules by 12-18 months or more. However, several of the ROD schedules are likely to be delayed an additional 6-12 months to incorporate EPA's National Remedy Review Board participation.

Initial Actions

Immediate Actions: In 1984, drums and contaminated soil in a drum disposal area were removed, and that site was capped. In addition, contaminants at the Main Base toxic waste disposal area were removed, and that site was re-graded. In the South Base storage area, tanks were excavated or filled with clean sand, and the area was re-graded. In 1989, a groundwater/fuel separation system was installed and put into operation. The system was designed to extract jet fuel from the groundwater. It was shut down when trichloroethylene (TCE) was discovered in the fuel, but was re-started in 1992 after pump replacement. A removal action at the Site 426, the suspected chemical warfare disposal site, was completed in November 2002. No hazardous materials or chemical waste were found during the removal action. The excavated soil and concrete were determined to be clean and were disposed of at Site 443.

Site Studies

Entire Base:
The Edwards AFB investigation into the nature and extent of contamination is currently winding down. Ten Operable Unit (OU) areas have been identified by the Air Force and seven are currently still in the Remedial Investigation/Feasibility Study (RI/FS) phase. One or more Records of Decision (RODs) will be prepared for each OU area and a total of 17 are projected by the Air Force for completion from 2003 through 2020. However, EPA has found that the Air Force schedules generally need an additional 12-18 months for realistic future predictions. Thus, EPA estimated completion dates used in this web page and in our CERCLIS database, maintained for EPA Headquarters and Congress, are later than the dates the Air Force estimates in the DoD database by roughly 15 months.
EPA tracks each ROD as a separate OU number in the CERCLIS database. Unfortunately, because of the complexity of the Edwards Site, EPA OU numbers do not exactly match Air Force OU identification numbers. Because Air Force document titles rely on Air Force numbers for OU areas, and to limit potential confusion, this web page uses the Air Force OU numbers in section and subsection headings, and provides the equivalent EPA OU number in italicized brackets at the end of sections that describe individual RODs.
Completion of some Site Studies have led to remedies being selected at 8 of the 17 OUs that EPA tracks. These are listed below in the "Remedy Selected" section, which will indicate the current status of remedy implementation, presented in one of several subsequent sections below.

Site Studies

Main Base/Flightline (OU1): In 1992, the Air Force began an investigation of the contamination found at the Main Base/Flightline. There are five main groundwater plumes on the flightline. Contaminants include VOCs and petroleum related products. Since completion of the RI Report in April 1996, various treatability studies including SVE/Air Sparging and dual extraction systems are in place at a few of the plumes in order to decrease levels of contamination in the source area. The FS report is complete (April 2008), although some issues surrounding a monitored natural attenuation alternative remain under discussion with EPA Headquarters and their National Remedy Review Board. In addition, the Air Force is currently investigating indoor air for likely refinements to the baseline risk assessment for the vapor intrusion pathway. In 2012 the Air Force determined that some groundwater plumes from neighboring OU8 are entering OU1 and mingling with at least one of the OU1 plumes. The Air Force now plans to amend the OU1 FS and combine these OU8 plumes into an FS Addendum and a combined OU1/OU8 Proposed Plan. The Proposed Plan will be made available to the public by 2019. EPA anticipates the ROD will be signed in 2020. [EPA OU 1]

South Base (OU2): This OU contains a variety of different types of sites and was initially described in the October 2004 RI Report and August 2005 FS Report. A Proposed Plan was provided for Public Comment in August 2006. Subsequently, this OU was divided into several different separate decisions based on new information considered by the FFA parties.1) South Base ROD (signed June 2009): See "Remedy Selected" section. [EPA OU 2] 2) South Base ROD Amendment for Sites 29 Landfill (signed September 2012): See "Remedy Selected" section. [EPA OU 13] 3) South Base Skeet Range Sites 81 and 102: These two sites were pulled out of the OU 2 ROD, described below in the "Remedy Selected" Section, and will be addressed in a future ROD by 2016. In the meantime, the Air Force is conducting some additional characterization of the sites to refine the original RI reported in October 2004. The Air Force will issue an Engineering Evaluation/Cost Assessment (EE/CA) to support a non time critical removal action in early 2016. [EPA OU 16]

Site Studies

Air Force Research Lab (AFRL) Sites (OU 4 & OU 9): The Air Force tested rocket engines at this remote ridge in the middle of the eastern part of the base. These OUs are grouped together due to the similar geology at these areas. Four major plume areas containing TCE, PCE and perchlorate have been identified in addition to a number of soil and debris sites associated with the operations. Five RODs are organized as follows.

1) South AFRL Groundwater ROD (signed September 2007): See "Remedy Selected" section. [EPA OU 4]2) AFRL Soil and Debris Sites ROD (signed August 2008): See "Remedy Selected" section. [EPA OU 11]3) Arroyos Groundwater ROD (OU4): This commingled plume area is located in the steep northwest part of OU 4. The RI and FS reports were completed in March 2005 and December 2008, respectively. In the August 2009 Proposed Plan, the Air Force proposed a TI ARAR waiver remedy similar to that of the South AFRL ROD, but possibly including a contingency for active groundwater extraction and treatment in the future event of plume migration outside containment zone boundaries. A new version of the draft final ROD will be reviewed in 2014. However, some additional characterization of potential containment zone boundary areas and associated issues are expected to result in lengthy discussions among the FFA parties. EPA anticipates the ROD will be signed by 2015 after final issues are resolved. [EPA OU 12]4) Northeast AFRL Groundwater ROD (OU 9): Two separate plume areas in OU 9 have slightly different hydro-geological conditions, and in 2010 the Air Force split them into separately planned RODs (see the next paragraph). Based on the January 2006 RI Report, the NE AFRL plume is being evaluated for a TI waiver in a draft FS to be submitted in 2014. The Air Force will offer a Proposed Plan for public comment in 2017. EPA anticipates the ROD will be signed in 2018. [EPA OU 9]5) Mars Boulevard Groundwater ROD (OUs 4&9): Originally part of the NE AFRL RI/FS project (RI Report completed in January 2006), the slightly different hydro-geology for this plume area caused the Air Force in 2010 to break it out for a separate FS and ROD. This area will be evaluated for a TI waive in an FS to be submitted in 2014. The Air Force will offer a Proposed Plan for public comment in 2017. EPA anticipates the ROD will be signed in 2018. [EPA OU 17]

Site Studies

North Base (OU 5 & OU 10, aka OU 5/10): There are three main groundwater plumes in the Occupied North Base (OU5). Contaminants consist of benzene and VOCs, as well as perchlorate. A groundwater extraction system using Ion Exchange has been operating at site 285 which has the perchlorate plume. Influent perchlorate concentrations averaged 450 ppb. As of early 2008, over 11.3 million gallons of groundwater have been treated and over 40 pounds of perchlorate has been removed from the site. Several miscellaneous soil and debris sites are located in the Unoccupied North Base (OU 10). Review of the draft FS report has led to the need for additional studies on nature and extent for some sites to supplement the July 2008 RI Report. An RI Addendum is currently under review. The FS will be completed by 2017, followed by a Proposed Plan in 2018. Meanwhile, the Air Force has conducted a time critical soil removal action for Site 231 due to Air Force mission critical needs for that location. A ROD addressing combined OU5/10 is anticipated for 2019. [EPA OU 5]

Basewide Miscellaneous (OU 7): This OU involves all sites and base areas not located in one of the other nine Air Force OU Areas. Combining this OU area with the other nine results in the total 301,000 acre area of Edwards AFB. There are three OU 7 areas currently under investigation and each will have a separate FS and ROD. The military munitions area may remain a separate Air Force program, although EPA will track and report it to Congress as a CERCLA OU. The four areas have RODs organized as follows. 1) Basewide Miscellaneous Sites ROD: A variety of sites around the base that do not fit inside any of the other nine OU areas are currently being assembled into a revised draft Proposed Plan, based on a June 2008 RI Report and a January 2010 FS Report. Some site-specific RI/FS Addenda will be reviewed in 2014. A final Proposed Plan will go to the public by 2018. EPA anticipates the ROD will be signed in 2019. [EPA OU 7] 2) Chemical Weapons Materiel (CWM) ROD (signed Sept. 2009): See "Remedy Selected" section. [EPA OU 15]3) Site 3 Landfill ROD:(signed Sept. 2012): See "Remedy Selected" section. [EPA OU 13] 4) Basewide Military Munitions ROD: The Air Force is currently in the equivalent of a CERCLA PA/SI phase of investigating possible locations of military munitions at various locations around the base. A draft RI Work Plan is due to regulators in 2014. It is unlikely that the Air Force will complete investigations and evaluations of alternatives before 2017. Thus, a final decision might come as late as 2019 or 2020. Although the Air Force currently resists placing this project under the CERCLA FFA, EPA is tracking it as a CERCLA OU. A controversial aspect of this OU area is the possibility that some privately owned acreage adjacent to the Edwards AFB fence line might have to be added to the total acreage associated with this NPL Site. Currently a removal action is targeting three locations with surface materiel that needs to be removed before further studies can be planned. The Air Force signed an action memorandum for this removal in February 2012. [EPA OU 14]

Site Studies

Northwest Main Base (OU 8): This area consists of five main groundwater plumes. All the plumes are migrating in the direction of OU1 and OU 6. One groundwater treatment system is currently operating. An RI Report was issued in March 2006 followed by an addendum in April 2008 for Sites 299 and 301. Site 25 is so heavily contaminated that it will be addressed by a separate ROD. The two RODs planned for OU8 are as follows.1) Miscellaneous Soil and Groundwater Sites ROD: This ROD will address Soil-Only Sites and groundwater at Sites 61, 299, and 301. Based on a July 2009 FS, the Air Force issued a draft Proposed Plan in late 2009 for regulatory review. However, many controversial issues related to monitored natural attenuation will need an extended time to resolve, in part because of similarities to OU 1 issues. In 2012 the Air Force determined that some groundwater plumes from neighboring OU8 are entering OU1 and mingling with at least one of the OU1 plumes. The Air Force now plans to amend the OU1 FS and combine these OU8 plumes into an FS Addendum and a combined OU1/OU8 Proposed Plan. The Proposed Plan will be made available to the public by 2019. EPA anticipates the ROD will be signed in 2020, possibly as a joint groundwater ROD with OU1 and possibly a separate ROD for the OU 8 soil remedies. [EPA OU 8]2) Site 25 ROD: Operations at an exotic fuel storage area led to a very large plume contaminated with petroleum commingled with TCE. Because the TCE was released into fractured bedrock as pure product, DNAPL contamination makes this a very difficult site to cleanup. A groundwater extraction and treatment system had operated as an interim containment measure for a portion of the leading edge headed into OU 6. A March 2011 draft final FS report and a related work plan resulted in extended discussions. A draft RI Report Addendum will be reviewed in 2014 followed by a revised FS report in 2016. A draft Proposed Plan could be ready for review in 2017. Involvement of EPA's National Remedy Review Board will likely result in a final Proposed Plan issued for public comment in early 2018. EPA anticipates the ROD will be signed in late 2018 or early 2019. [EPA OU 10]

Completed Site Studies: All OU RI reports, except for the MMRP OU areas, have been completed, although some current site-specific investigations will be reported in future addenda to previous RI or FS reports. Dates for already completed Final RI and Final FS reports are included, along with completed Proposed Plan dates, in the following "Remedy Selected" section.

Remedy Selected

South Base (OU 2): On June 24, 2009 EPA signed a ROD for cleanup of 3 groundwater plumes involving 4 source sites and containment of a landfill site. Four other sites were identified for no action. These decisions were based on the October 2004 RI Report and August 2005 FS Report. A Proposed Plan was provided for Public Comment in August 2006. The main contaminants of concern for this OU are TCE, PCE and BTEX. (see remedy details in the "Remedy Design" section below).

South Base Site 29 Landfill (OU 2): On September 27, 2012 EPA signed a ROD Amendment replacing containment of the landfill site with clean closure remedy instead. A Proposed Plan for this amendment was provided for Public Comment in December 2010. (see remedy details in the "Remedy Design" section below). [part of EPA OU 2].

Basewide Wells (OU 3): The Air Force completed a survey of all historic wells and Air Force wells installed prior to the CERCLA investigations. Only eight needed further investigation and were described in the December 1999 RI Report. A No Further Action Proposed Plan was provided for Public Comment in June 2003. On September 30, 2003 EPA signed a ROD for No Further Action. [EPA OU 3].

South AFRL Groundwater Plumes (OUs 4&9): On September 28, 2007 EPA signed a ROD for a Technical Impracticability ARAR Waiver and vapor intrusion LUCs. These decisions involved four source sites and were based on the March 2005 RI Report and June 2005 FS Report. A Proposed Plan was provided for Public Comment in April 2006. The main contaminants of concern for this OU are TCE, PCE, 1,4 dioxane, perchlorate, benzene and NDMA. (see remedy details in "Ongoing Cleanup" section below). [EPA OU 4].

AFRL Soil and Debris Sites ROD (OUs 4&9): On August 8, 2008 EPA signed a ROD that selected soil and debris remedies for 8 sites located throughout OU4 and OU9. Another 10 sites in these OUs were designated as no action sites. These decisions were based on the March 2005 OU4 RI Report, January 2006 OU 9 RI Report, and August 2006 FS Report. A Proposed Plan was provided for Public Comment in March 2007. The main contaminants of concern among these soil and debris sites are PCBs, beryllium, perchlorate, and PAHs. (see remedy details in "Ongoing Cleanup" section below). A 2013 Explanation of Significant Difference for PCB site 312 will document the end of excavation and the use of LUCs for a small amount of in contaminated soil inaccessible beneath a currently established transformer foundation. [EPA OU 11].

NASA Dryden (OU6): On September 28, 2006 EPA signed a groundwater cleanup ROD involving 3 source sites. Three other sites were identified for no action. These decisions were based on the November 2000 RI Report and August 2004 FS Report. A Proposed Plan was provided for Public Comment in August 2005. The main contaminants of concern for this OU are TCE, and benzene. (see remedy details in "Ongoing Cleanup" section below). [EPA OU 6]

Chemical Weapons Materiel Sites ROD (OU7): On September 16, 2009 EPA signed a ROD that addresses three separate ordnance debris burial areas associated as Site 442. Another area (Site 426) was designated as a No Action Site. These decisions were based on the July 2006 RI Report and August 2007 FS Report. A Proposed Plan was provided for Public Comment in April 2008. (see remedy details in the "Ongoing Cleanup" section below). [EPA OU 15]

Site 3 Landfill ROD (OU7): On September 21, 2012 EPA signed a ROD that addresses the Main Base Inactive Landfill and limited groundwater plumes still closely associated with fringe parts of the landfill footprint imposed over the deeper fractured bedrock location of the plumes. This decision was based on the June 2008 OU 7 RI Report, the site-specific October 2008 FS, the December 2009 FS Addendum, and the Proposed Plan issued in February 2010. (see remedy details in the "Remedy Design" section below). [EPA OU 13]

Remedy Design

South Base (OU2): The Air Force began investigations of the South Base in 1992. The South Base was abandoned and almost completely demolished in the 1960s. The 2009 ROD addresses 3 groundwater plumes with containment and cleanup, and addresses a closed landfill with an improved cover and monitoring program in addition to LUCs. Some response actions (called Phase 1 by EPA) at one of the plumes and at the landfill were begun voluntarily by the Air Force before the ROD was signed.
The Air Force began designing the groundwater remedy for Site 86 earlier in 2009. It is now under review. Additional design documents for the Site 29 landfill, and Site 76 groundwater plume were submitted in 2010. The series of RD/RA work plans submitted after the ROD are considered Phase 2 work by EPA, because some voluntary response actions at one of the plumes and the landfill were begun prior to the ROD. A design phase investigation at the Site 29 landfill resulted in some significantly reduced estimates of the size of the landfill. The Air Force then considered amending the ROD and released a new Proposed Plan to clean close the landfill instead of using the containment cover remedy selected in the 2009 ROD. The ROD was officially amended in late 2012.
A draft remedial design document and work plan is currently under development by the Air Force for the clean closure of the Site 29 landfill. EPA anticipates a completed design and the beginning of field work in 2014. [EPA OU 2]

Site 3 Landfill ROD (OU7): A draft remedial design document and work plan is currently under development by the Air Force for the consolidation beneath an evapo-transpiration cover of the Site 3 Landfill. Due to an Air Force conversion to performance based remediation contracts, EPA anticipates a completed design and the beginning of field work in 2018. [EPA OU 13]

Completed Designs: Four of the five signed Action RODs have completed Remedial Designs on the following dates:
OUs 4&9 South AFRL on 6/12/09,
OUs 4&9 AFRL Soil and Debris Sites on 9/28/09,
OU 6 NASA Dryden on 2/15/08, and
OU 7 Chemical Weapons Materiel Sites on 11/9/10.

Cleanup Ongoing

South AFRL (OU 4&9): The remedy does not involve ongoing cleanup, although the Air Force will continue monitoring eventual containment of the solvent and perchlorate contaminated plumes by natural attenuation and will continue maintaining land use controls within the Containment Zone. Monitoring of plume migration is also used to determine where land use controls need to be applied to protect buildings from vapor intrusion into indoor air.
A final RD/RA Work Plan was approved by EPA in June 2009. Groundwater monitoring is already underway from the pre-ROD program and will be refined per RD/RA Work Plan specifications. A vapor intrusion sampling program was designed as part of the above RD/RA Work Plan. Upon completion of the Interim RA Report in October 2009, the long-term O&M phase officially began. The first five year review of this remedy was completed in September 2012. [EPA OU 4]

AFRL Soil and Debris Sites (OUs 4&9): Cleanup work in the field was begun voluntarily by the Air Force before the ROD was signed. Now all 8 of the action sites are being addressed by implementation of the September 2009 RD/RA Work Plan. The first five year review of this remedy is due in August 2013. Contaminated groundwater associated with these sites will be studied and addressed by one of the four other AFRL RODs described earlier in this fact sheet. A 2013 Explanation of Significant Difference for PCB site 312 documented the end of excavation and the use of LUCs for a small amount of in contaminated soil inaccessible beneath a currently established transformer foundation. The Air Force will consider final cleanup of this soil whenever the transformer is decommissioned and dismantled. [EPA OU 11]

NASA Dryden (OU6): There is a commingled plume primarily contaminated with TCE and PCE. The 2006 ROD requires injection of chemical oxidation reagents into groundwater to degrade chlorinated hydrocarbons and enhanced natural attenuation of aromatic hydrocarbons to MCLs. All soil sites are determined to require no action. The first phase of remedy implementation began as a treatability study that became full scale in 2005. The second phase involving annual injections of oxidation reagents is now underway in accordance with the February 2008 Remedial Design. A five year review of this remedy was submitted in September 2011. EPA deferred the Five Year Review Protectiveness Statement until the Air Force provides some additional data and analysis in a Five Year Review Report Addendum expected in 2014. Critical sampling of the vapor intrusion pathway is currently underway and a new risk assessment is planned for late 2014. [EPA OU 6]

Chemical Weapons Materiel Sites (OU7): Soils and groundwater do not appear to be significantly contaminated. The main hazard is the potential for unexploded ordnance. Existing covers and fences will be strengthened. A final RA Report was issued 2013. The first five year review of this remedy is due in September 2014. [EPA OU 15]

Cleanup Complete

None of the Operable Units at Edwards is fully cleaned up. However one operable unit (OU 3 Basewide Wells) and a number of individual sites were determined in various RODs to need No Further Action because previous interim response actions reduced contamination to levels below action levels selected for the particular ROD addressing the particular OU area or site.

Edwards Air Force Base is participating in the Installation Restoration Program, a specially funded program established by the Department of Defense (DOD) in 1978 to identify, investigate, and control the migration of hazardous contaminants at military and other DOD facilities. Because of the protracted schedule required to complete long-term cleanup activities, the base Environmental Program has proposed initiating an aggressive removal action program and began its implementation in 1995. The interim actions are on-going and the Air Force is completing the investigations at all the sites. OU specific RODs will be developed to select the final actions for each site. The State of California and the EPA are in agreement with this approach. The first eight RODs have been signed: OU 3 in August 2003, OU 6 in September 2006, OU 4 &9 South AFRL in September 2007, and OU 4 &9 AFRL Soil and Debris Sites in August 2008, OU2 South Base in June 2009, OU 7 Chemical Weapons Materiel Sites in September 2009, OU 7 Site 3 Landfill in September 2012, and an Amendment for OU 2 South Base in September 2012.

Cleanup Results to Date

The removal of drums, tanks, and contaminated soils has reduced the potential of exposure to hazardous substances at the Edwards Air Force Base site while investigations are taking place and cleanup activities are being planned. Many OUs currently have significant treatability studies involving groundwater and soil vapor extraction and treatment, with ongoing monitoring and reporting. For example, a significant amount of source removal has already been conducted by the Air Force at OU 1 groundwater and soil areas. The OU 6 ROD groundwater cleanup action is underway and the OU 2 South Base ROD groundwater cleanup is partially underway (Phase 1) at the Sites 5/14 plume.

Documents and Reports

Community Involvement

Public Meetings: Restoration Advisory Meetings held quarterly on the last Thursday of the month at Edwards AFB.
Report to Stakeholders is available in the public information repository or can be mailed by contacting the Air Force at 661-277-1466